Recent trends towards lighter and more efficient commercial aircraft have motivated airframers to consider the use of electromechanical actuators EMA as the primary means of power for aircraft flight control systems. The transition from state-of-the-art hydraulic actuation to new electromechanical technologies poses a great challenge to both airframers and system suppliers for the correct and complete definition of new requirements. Transient effects such as electric motor overheating and inertial loads, previously not present or irrelevant for hydraulic actuators, now have to be taken into account. A knowledge-based environment containing design drivers for electromechanical components is combined with a validation method in order to aid the systems engineer to accomplish such task. This approach offers the potential to guarantee that all requirements are covered by a new technology, and that they are complete and consistent. In addition, analyzing representative mission profiles and extracting relevant flight data aid in the identification of active design drivers and speeds up requirement definition for the technology under consideration. These concepts are illustrated with a case study of a short-range aircraft's aileron EMA. Methods and tools described herein are being developed within the framework of the European research project Actuation 2015 which aims at the standardization of EMA components for aerospace applications.